A First Measurement of the Coherent Elastic Neutrino-Nucleus Scattering Cross Section

对基本粒子性质的精确实验测试现在是一种行之有效的方法，可以在我们现有的物理知识之外寻找新的自然定律。粒子相互作用的标准模型描述了已知的基本粒子及其相互作用。然而，最简单形式的标准模型并不包括非零质量的中微子，现在已经有实验证明了这一点。这就要求我们继续努力改进标准模型，并进一步了解中微子的性质和相互作用。中微子从原子核中散射，使原子核保持完整，这在大约40年前首次被描述，但仍然缺乏实验证明。按照这里的计划，对中微子相互作用模式的精确测量将提供对几个仍然不受约束的中微子性质的处理，有助于制定对标准模型的改进。这项研究将使用钠掺杂碘化铯作为探测相干弹性中微子-核散射的有利目标，利用来自橡树岭国家实验室的高能中微子。这种材料对低能量核反冲的反应，就像这一过程中预期的反应一样，已经得到了表征，并在专用辐射屏蔽中使用2公斤低本底原型晶体进行了全面的可行性测试。根据这些研究，计划中的14公斤探测器预计每年将测量这种中微子相互作用模式产生的大约550个事件。在授标期间，还将研究Pb-208上尚未测量的产生中子的荷电中微子相互作用，这对核物理和超新星探测很有意义。

Precise experimental tests of fundamental particle properties are now a well-established way to search for new laws of nature beyond our current physical knowledge. The Standard Model of particle interactions describes known fundamental particles and their interactions. However, the Standard Model in its simplest form does not include a nonzero mass of the neutrino, for which there is now experimental proof. This calls for a continued effort to improve the Standard Model, and to further our knowledge of neutrino properties and interactions. Neutrino scattering from the nucleus, which leaves the nucleus intact, was first described some forty years ago, but still lacks an experimental demonstration. An accurate measurement of this mode of neutrino interaction, as planned here, will provide a handle on several still unconstrained neutrino properties, contributing information that helps to formulate refinements to the Standard Model.This research will use sodium-doped cesium iodide scintillators as an advantageous target for the detection of Coherent Elastic Neutrino-Nucleus Scattering, exploiting the intense neutrino yield from the Spallation Neutron Source facility at Oak Ridge National Laboratory. The response of this material to low-energy nuclear recoils, like those expected from this process, has been characterized and a full feasibility test has been performed using a 2 kg low-background prototype crystal in a dedicated radiation shield. Based on these studies, a planned 14 kg detector is expected to measure approximately 550 events per year from this mode of neutrino interaction. The still unmeasured neutron-generating charged-current neutrino interaction on Pb-208, of interest in nuclear physics and for supernova detection, will also be studied during the period of the award.